858SSB MODULATION METER

++++++++++++++++++++++++++++++++++++++++

The circuit traces for a modulation meter are already on the board, as  a mod meter was a feature on some 858ssb sets (Cobra 139XLR, for example).

 First, install the following parts into the board.

C169 .0047uf disc,   C224  1uf/50v electrolytic,   C225  .0047uf discm  C226  1uf/50v electrolytic (see text).   D55  1N60P diode,   R203  10kohm 1/4w,   VR4  100kohm PC pot,  

 Then get a high quality illuminated VU meter (Simpson, Triplett, Sony, etc.) with a 1ua movement and mount it in a meter case.  On my TRC457, I ran the Mod meter output , a 6vdc source (for the meter light) ,  and ground to a miniature stereo RCA jack on the rear panel. If you use a good meter and housing, it makes for a nice addition to yout station setup.      ****NOTE***  The function of C226 is to keep rhe meter needle from bouncing around too much. Since the audio speech clipper in the 858s holds the modulation pretty steady anyway, adding a little bounce to the meter actually looks pretty cool. I reduced the value of C226 to .47uf/50v. If you can't find a .47 electrolytic, just gook two 1uf caps in series (observe polarity).